The invention relates to a camera with an electrical shutter, and more particularly, to such a camera having an electrical shutter of non-memory, TTL (through the lens) photometry type in which the shutter is forcibly closed under an underexposure condition when an electronic flash is mounted on the camera to take a picture under flashlight illumination.
When an electronic flash is mounted on a camera having an electrical shutter of non-memory, TTL photometry type, there are a number of operating schemes depending on the choice of a particular signal which is used to close the shutter, However, these schemes suffer from various disadvantages.
Specifically, when an exposure period under a flashlight illumination is preset on the camera so that synchro contacts are closed at the termination of the running of a first shutter blind and at the beginning of running of a second shutter blind, it is likely that the shutter will be closed without involving a flashlight illumination from the electronic flash as a result of an insufficient charging of a main capacitor or a user having forgotton to load a power supply, thus resulting in a failure to take a picture.
In an alternative arrangement, a fixed exposure period may be established at the time the electronic flash is mounted on the camera or at the completion of a charging operation of the main capacitor thereof. In this instance, there takes place no detection of a flashlight illumination from the electronic flash, so that the shutter can be closed without an operation of the illumination circuit, again resulting in a failure to take a picture. In addition, because the photometric function provided on the part of the camera is not activated, the exposure is solely controlled by the electronic flash. This may result in an overexposure when an object being photographed is under bright illumination, destroying the vary purpose of a camera of TTL photometry type.